PCB Technical - Types of SMT reflow oven in PCB board

SMT reflow oven is the main soldering equipment in SMT assembly.Soldering is one of the most critical processes in SMT.The performance of the equipment has a direct impact on the quality of soldering.In particular, the current lead-free soldering has the characteristics of high temperature, poor wettability,and small process window. Lead-free reflow oven selection should be more cautious. There are many types of reflow ovens,such as hot plate reflow ovens,infrared reflow ovens,hot air reflow ovens, infrared hot air reflow ovens, gas phase reflow ovens, etc.that heat the entire PCB; laser reflow ovens and focused infrared reflow ovens are used for local heating of PCBs.,Hot air flow reflow oven, etc.

SMT reflow oven that heats the entire PCB

The hot plate reflow oven was used in the early days of SMT.Due to the low thermal efficiency of this type of reflow oven, the uneven heating of the PCB surface and the special sensitivity to the thickness of the PCB,it was quickly replaced by other reflow ovens.Infrared reflow ovens were popular in the 1980s. When infrared radiation radiates,dark-colored components absorb more heat than light-colored components, and infrared rays do not have the ability to penetrate.Components in shadow areas blocked by large components cannot easily reach the soldering temperature, resulting in a large temperature difference on the PCB substrate, which is unfavorable for soldering.

Therefore, it is basically Need not. 

The hot air smt reflow oven has been used since the mid-1980s and has continued to this day. In recent years, the hot-air reflow oven has adopted various measures in airflow design, equipment structure, materials, software and hardware configuration, etc.Therefore, the all-hot-air reflow oven has become the first choice for today's SMT reflow oven. Infrared hot air reflow oven means that the heating source has both hot air and infrared rays.Due to the high soldering temperature of lead-free soldering, the reflow zone is required to increase thermal efficiency, so infrared heaters are added at the entrance of the hot blast stove and the bottom of the reflow zone, which not only solves the problems of high soldering temperature and speeds up the heating rate, but also saves energy. 

Therefore, the infrared hot air stove also has a certain utilization rate in today's lead-free soldering. The gas phase reflow furnace was used in the early 1970s,but due to the high cost of equipment and media, it was quickly replaced by other methods.However,the gas-phase reflow furnace has the advantages of accurate temperature control,heating media with different boiling points to meet different soldering temperatures of various products,high heat conversion efficiency, rapid heating, oxygen-free environment,uniform temperature throughout the PCB, and good soldering quality.Therefore,with the development of lead-free,the gas-phase reflow furnace has once again attracted people's interest,and is used for high-reliability and difficult-to-heat surface mount boards.

SMT reflow oven that locally heats the circuit board

The laser beam reflow oven utilizes the excellent directivity and high power characteristics of the laser beam.The laser beam is concentrated in a small area and within a short period of time through the optical system,so that the welded part forms a highly concentrated local heating zone.A kind of smt reflow oven.During the soldering process, the substrate and the component body are kept at a lower temperature,the soldering stress is low, and the components and the substrate will not be damaged. However, because the equipment is very expensive, it is only used for thermal components,precious substrates and fine pitch Local welding of components. Focused infrared reflow ovens are generally suitable for rework stations for rework or partial soldering. Hot air flow reflow furnace refers to a type of reflow furnace in which air or nitrogen is introduced into a special heating head and hot air flow is used for welding.This kind of smt reflow oven needs to process nozzles of different sizes for different sizes of solder joints, and the speed is relatively slow, so it is mainly used for rework or development.

In SMT assembly, the choice and application of reflow oven is undoubtedly a key factor affecting product quality and productivity. With the wide application of lead-free soldering technology, the requirements for reflow ovens are increasing. From the full hot air reflow oven that heats the entire PCB to the reflow oven that utilizes laser beam and focused infrared technology for localized heating, each type of equipment has its own unique application scenarios and advantages.

When choosing a smt reflow oven,it is important to consider not only its heating efficiency and temperature uniformity, but also the actual needs of the production line, such as product type, production volume,cost budget and other factors.At the same time,with the progress of science and technology, the degree of intelligence and automation of reflow oven is also improving, providing more possibilities for SMT assembly.